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Cells/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby. An animation shows a man, Tim, and a robot, Moby, looking at a green toy dinosaur assembled out of many small pieces. TIM: Hey, I need one of those eight by two pieces. Moby holds up a green block in the shape of a cube. It appears to have four dots on the top face arranged in a two by two array. TIM: No … no, eight by two. Eight dots long and two dots wide. Moby puts down the green block and picks up a piece of paper which he hands to Tim. Tim reads from a typed letter. TIM: Dear Tim & Moby, My sister said my body is made of cells. Is this true, and just what the heck are cells, anyway? From Jenny. TIM: Well, your sister was right. You are made of cells. She's made of cells, too. In fact, all living things are made of one or more cells—they’re the building blocks of life. If you could look at yourself through a microscope, you could see that you’re divided into millions of tiny . . . tiny sections. These sections are called cells. An image shows a cluster of many cells, as if looking through a microscope. The cells are generally oval in shape, but they are not all shaped exactly alike. Each cell has a green oval in its center. A caption reads: cells. TIM: Cells live with other cells like them in groups called tissues. This here is a typical cell. An image shows a single cell. The cell is cut into cross-section and one half is removed so the interior of the cell is visible. The cell has a thin band around the perimeter. Five objects can be seen within the cell. In the center is a circle with a blue sphere in it. A brown object that looks like a maze is attached to the inner circle. There is a purple, oval shaped object with many folds within. There is a row of four long, thin worm-like shapes of varying lengths. The other two are spherical shapes, one with five tiny spheres within. TIM: It's basically a blob of jelly-like fluid called cytoplasm, surrounded by a cell membrane. The text “cytoplasm” appears over the space between the two circles. The text “membrane” appears next to the thin band around the perimeter. TIM: The membrane lets good stuff in and keeps bad stuff out. Floating around in the cytoplasm are organelles. The text “organelles” appears. The color of the five objects between the two circles fades to white. TIM: These little guys do all the work that cells need to do, like make proteins, turn food into energy, and get rid of waste. MOBY: Beep. TIM: Right, just like the body has organs for different functions, the cell has organelles for its functions. An animation shows a screen divided in two. The torso of a human is shown in the right frame. Organs such as lungs, stomach, kidneys, and intestines can be seen. The left frame shows a cross-section of a cell. Organelles can be seen within the cell. TIM: To remove waste, your body has the kidneys and intestines. In the right frame, the kidneys flash. The text “kidneys” appears. Then the intestines flash. The text “intestines” appears. TIM: A cell has lysosomes and peroxysomes. The sphere with five tiny spheres in it flashes. The text “lysosomes” appears. The other sphere flashes. The text “peroxysomes” appears. MOBY: Beep? TIM: Hey, good question—a cell’s “brain” is its genetic material—DNA and RNA. An animation of UpperWord D N A is shown. It looks like two interleaved spirals with bars connecting them. Each bar is made of two halves that are locked together. Each half of the bar is a different color. Text reads: UpperWord D N A. Another animation appears that is identical to one half of the UpperWord D N A cut lengthwise down the center. Text reads: UpperWord R N A. TIM: Genes are like a computer program that controls all of an organism’s functions. An animation shows a screen divided in two. On the right is an image of electronics. On the left are two oblong objects each consisting of two solid blue ovals attached end-to-end vertically. The upper oval is smaller than the lower one. TIM: The genetic material inside each cell coordinates all of its actions. The left frame expands to fil the screen and we now see 23 pairs of these objects. TIM: Plants and animals, including people, are made of eukaryotic cells, which mean their genetic material is surrounded by a membrane. The animation zooms out to show that the 23 pairs of genetic material are surrounded by a membrane. Text reads: eukaryotic cells. TIM: Together, the genes and the membrane form an organelle called the nucleus. The genetic material and its surrounding membrane are highlighted. Text reads: nucleus. TIM: The other type of cell, prokaryotic, has no nucleus. Genetic information in prokaryotic cells just sort of floats free in the cytoplasm. An animation shows an oval-shaped cell moving across the screen. A long wiggling tail propels the cell across the screen. Genetic material can be seen inside the cell. Text reads: prokaryotic. TIM: Most prokaryotes are single-celled bacteria, like Lactobacillus acidophilus, which is used to make yogurt. An animation shows a group of long oval-shaped cells. The view zooms out to show a container labeled “yogurt.” The animation switches back to Tim and Moby. MOBY: Beep? TIM: Nope, not all cells look like these. In any given organism, different cells carry out very specialized functions. As a result, they can look very different. Some types of bone cells are star-shaped. The screen becomes black. In the upper-left quadrant is a bone cell. TIM: Muscle cells have to be stretchy. In the upper-right quadrant is a muscle cell. It is thin and elongated. TIM: Nerve cells can be really long, so they can carry signals from one part of the body to another. In the lower-left quadrant is a nerve cell. It is long and wiry with a tree-like structure on one end and a flattened semi-circular shape with long tendril-like structures radiating outward on the other. The wiry portion is covered with many cylinders. TIM: This bacteria has little hairs growing out of its membrane to help it move around. In the lower-right quadrant is an oblong pill-shaped cell with a large number of hairs extruding from its body. TIM: Red blood cells are sort of shaped like little bowls. An animation shows many red blood cells floating through a cross-section of a tubular structure. TIM: Plant cells have a rigid cell wall that maintains their shape. A collection of green cells is shown. Each contains many organelles. By one of the cell’s outer membanes, the text reads: cell wall. The view switches back to Tim. TIM: Inside the human body, cells range from microscopic to over a meter long! You have about 75 trillion cells in your body, enough to stretch around the earth 47 times. An animation of the earth is shown. A band begins to encircle the earth going around again and again until several circular bands are formed around the image of the earth. The view switches back to Tim and Moby. MOBY: Beep! TIM: Yeah … yeah, I guess that would hurt. MOBY: Beep? TIM: Okay, whether they’re eukaryotic or prokaryotic, almost all cells have the ability to divide. In eukaryotes, the process is called mitosis. The nucleus splits apart . . . the cell stretches out . . . and then separates into two distinct cells. An image of a cell is shown. A cell wall and a nucleus can be seen. The nucleus divides into two identical parts and each moves to opposite ends of the cell. The cell divides until it also forms two identical parts. A cell wall forms to encircle each new cell. Within each new cell is a nucleus in the center. TIM: This is how you grow. MOBY: Beep. The view shifts to Tim and Moby looking at the green toy dinosaur. Moby points a finger at the dinosaur. A yellow ray emanates out of his finger and strikes the dinosaur. The dinosaur splits into two identical dinosaurs. TIM: Hey … hey cut that out. 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